Shyren

She use to swim through the lakes attacking anything that entered until she went after undyne and met the end of her spear

If she survived:
Shyren would still rule her streams if any prey got close to her waters she would jump out and bite any part of the creatures body and drag them in pulling them underneath the water until they drowned while the creatures underwater shyren would rip bits of there flesh off torturing the poor creature.